We're accustomed to reading about how quickly faraway rainforests are disappearing - so many acres every day.

But much closer to home, the National Forest Service has a similar caution, this time concerning open space.

According to that agency's figures, the United States loses about 6,000 acres of open space every day, or four acres per minute.

It is difficult for many of us to get worked up about the threat to open space, particularly people in places like Montana, which is pretty much made of the stuff. But even Helenans are watching as housing developments and commercial development relentlessly turns crop land and pastures and once wild mountainsides into yet another urban footprint.

That's why, in recent years anyway, local efforts to purchase property solely to preserve its undeveloped nature have been successful. Enough people didn't want to lose the city's wild visual backdrop to urban sprawl.

The Forest Service, concerned with open space on a national scale, is developing a strategy to protect and conserve it by working in partnership with private landowners and state and local government to identify areas most in need of protection. The agency also will work with Congress to create tax breaks and other incentives to promote conservation in ecologically sensitive areas.

That program would augment, certainly not replace, the agendas of the Nature Conservancy and other similar organizations that already promote ways in which landowners can preserve their wild properties for future generations.

Unlike bacteria thoughtlessly multiplying in a Petri dish or rats blithely breeding in a laboratory cage, we can extrapolate the environmental impacts of present growth trends. Development of course will continue, but it matters where. The program announced by the Forest Service last week recognizes both those facts.